The present invention relates to a method and an arrangement for flick ramming shells and propellant powder charges in artillery pieces which are loaded with these components separately.
The expression flick ramming means that the components making up the charge, in the form of shells and propellant powder charges, are, during the start of each loading operation, imparted such a great velocity that they perform their own loading operation up to ramming in the barrel of the piece in more or less free flight at the same time as the loading cradle in which they are accelerated to the necessary velocity is rapidly braked to a stop before or immediately after it has passed into the loading opening of the barrel.
Flick ramming is an effective way of driving up the rate of fire even in heavier artillery pieces, and, in this connection, it is in general terms necessary for the shells, for example, to be imparted a velocity of at least approaching 8 metres per second in order for flick ramming to be performed. It is moreover desirable that the ramming velocity can be varied in relation to the elevation of the piece so that the shells are always rammed equally firmly in the loading space of the piece. This is because, in this way, variations of Vo, that is to say the muzzle velocity, as a result of shells/projectiles being rammed with varying degrees of firmness are avoided.
The major problem associated with flick ramming heavier artillery shells/projectiles is that of accelerating these to the necessary final velocity within the acceleration distance available, which is usually no longer than the length of the shell or projectile itself. Furthermore, it must be possible to flick ram different types of shell/projectile of different weight and length using one and the same rammer. A further complication in flick ramming shells/projectiles, and to a certain extent in flick ramming propellant powder charges, is that, as soon as they have reached the desired velocity, the rammer or the shell cradle with which they have been accelerated to the desired flick ramming velocity must be rapidly braked to zero while the accelerated shell or propellant powder charge continues its course forwards and into the loading opening of the piece as a freely moving body.
Thus far, the practice has primarily been to use pneumatically driven flick rammers in which a pneumatic accumulator provided the necessary energy to impart the requisite flick velocity to the shell in question. In conventional rammers which do not provide flick ramming, there are often chain transmissions for transferring the energy supply between an axially displaced hydraulic or pneumatic piston and the rammer which acts directly on the rear part of the shell.
U.S. Pat. No. 4,457,209, in which chiefly FIGS. 12 and 18 are of interest, can be cited as an example of a hydraulically driven shell rammer, while U.S. Pat. No. 4,957,028 constitutes an example of a purely piston-driven rammer.
The present invention relates to an electrically driven flick rammer for artillery pieces. The rammer according to the invention is to begin with characterized in that, for the acceleration of the shells and, where appropriate, the propellant powder charges, it utilizes the starting acceleration from an electric motor, the rotating movement of which is mechanically geared down and converted into a rectilinear movement. According to a development of the invention, it is moreover possible, when necessary, to make use of an extra energy supply from a chargeable energy accumulator which has previously been provided with an energy supply and is then triggered simultaneously with the driving electric motor of the flick rammer being started, and which thus makes even more rapid acceleration possible. In one of the exemplary embodiments which illustrate the invention, the ramming velocity obtained according to the basic principle of the invention is geared up by a specific mechanical arrangement.
The basic construction of the electrically driven flick rammer according to the invention can therefore be used for ramming both shells and propellant powder charges, the difference being chiefly that, as far as ramming shells is concerned, it is as a rule only these which are accelerated to flick velocity in a fixed loading cradle, whereas, in the case of propellant powder charges, it may be necessary to accelerate the loading cradle as well and allow it to follow the charges into the loading opening of the barrel because the propellant powder charges may have poor inherent rigidity.
The advantages of driving the rammer electrically instead of hydraulically or pneumatically include the fact that the rammer can thus be made much more simple and have fewer component parts and can thus be expected to have a greater degree of availability, at the same time as it becomes possible, by means of electronic control of the driving electric motor, to adjust the ramming velocities accurately at all the elevations of the piece, so that ramming is always the same. The electric motor can therefore also be used to brake the ramming velocity in the event that the energy supply provided by the energy accumulator is too great in relation to the piece elevation at the time.
The basic idea underlying the present invention is therefore that, for loading artillery pieces, use is to be made of the starting acceleration of an electric motor in order to accelerate the artillery propellant powder charge or the shell to be loaded into the piece to such a great velocity that it is sufficient for flick ramming the same. For this to be possible, the rotating movement of the electric motor must, as already mentioned, be converted into a linear movement. In connection with the invention, two different basic principles for this are proposed, one of which is based on the use of a drive belt or feed chain driven by the geared-down electric motor via preferably a bevel gear or a planetary gear, while the other is based on the use of a pinion which is connected to the electric motor and drives a rack in the desired axial direction. The invention also includes a method and a number of arrangements which make possible electrically driven flick ramming of both propellant powder charges and shells, in which the energy supply from the electric motor is combined with that from the energy accumulator, the accumulated energy of which is discharged at the same time and parallel to the motor being started. As the shells have such a great dead weight, an energy supply of not inconsiderable magnitude is necessary in addition to an electric motor, which gives rise to a linear movement in the manner already indicated, so as to keep the size of the motor within reasonable limits. According to the basic concept in question, the energy supply which is therefore necessary in addition to the motor is provided by triggering the energy accumulated in an energy accumulator simultaneously with the electric motor being started. During acceleration itself, the shells must have a certain support in the form of a shell cradle, and, in this, they are accelerated to the desired ramming velocity by a shell rammer. The latter must in turn be stopped rapidly before it arrives in the loading opening of the piece. Some of the braking energy developed in this connection can then be used for at least partial recharging of the energy accumulator. According to a preferred development of the invention, the electric motor, which constitutes the core itself of the system, can subsequently be used to complete the recharging of the energy accumulator. In this connection, the simplest way of carrying out this recharging of the energy accumulator is to reverse the electric motor, the other parts of the rammer then following. In addition to the electric motor and the energy accumulator, the rammer according to the invention also requires a locking function which ensures that the energy accumulator is triggered at the correct moment, that is to say simultaneously with the electric motor being started. In this connection, the motor can be used to provide the locking function. The part referred to above as the energy accumulator can advantageously consist of a compressible spring means in the form of one or more interacting coil or pneumatic springs of a type known per se provided that it is possible to achieve sufficient energy accumulation capacity with these.
As already indicated, the basic idea of the electric motor-driven rammer, with its energy accumulator for making possible ramming of even heavy shells, allows scope for a number of different detailed embodiments. There are therefore a number of different ways in which the accelerating rotation of an electric motor can be converted into a likewise accelerating rectilinear movement, at the same time as there are a number of different ways of embodying the energy accumulator. A few different preferred ways of embodying the arrangement according to the invention will therefore be described in greater detail below. One of the examples described also comprises, in addition to the basic concept of the invention, a development of the same which makes possible mechanical gearing-up of the ramming velocity to a higher level than is achieved according to said basic concept. The variants described in connection with the appended figures are, however, to be seen only as examples of a few embodiments of the invention, while the latter is as a whole defined in the patent claims below.